You can do this using regex easily.

public static char[] getDigits(char[] charArray) {
    Pattern p = Pattern.compile("-?\\d+");
    Matcher m = p.matcher(String.valueOf(charArray));
    String str=new String();
    while (m.find()) {
       str=str+m.group();
    }
    return str.toCharArray();
}

Demo

You can do this using regex easily.

public static char[] getDigits(char[] charArray) {
    Pattern p = Pattern.compile("-?\\d+");
    Matcher m = p.matcher(String.valueOf(charArray));
    String str=new String();
    while (m.find()) {
       str=str+m.group();
    }
    return str.toCharArray();
}

Demo

Again you can do this easy in following way too.

 public static char[] getDigits(char[] charArray) {
  String str=new String();
  for(int i=0;i<charArray.length;i++){
      if(Character.isDigit(charArray[i])){
          str=str+charArray[i];
      }
  }
  return str.toCharArray();
}